One remarkable feature of T. brucei is the efficient transport of proteins. Furthermore the parasite possesses only a reduced number of trafficking pathways compared to mammalian cells. Combined with the defined cell architecture of the protozoon exhibits unique advantages to study the trafficking especially of GPI-anchored proteins. Furthermore T. brucei passes through various life cycle stages, which differ extremely in their requirements concerning the endosomal compartment. The establishment of an RNAi-assay in order to characterize the trafficking pathway of GPI-anchored fluorescent reporter proteins lead to the identification of various sorting steps. These sorting steps consist of the trafficking of GPI-anchored proteins from ER to the golgi via COP I-vesicles, the blockes access of non-VSGs from the pellicular cell membrane, and the possible separation of VSGs and non-VSGs close to lysosome and golgi. Furthermore this thesis produces the basics for the characterization of the poor characterized life cycle stage of short stumpy BSF.